Embodiments relate generally to marine geophysical surveying and, more particularly, embodiments relate to coupling a heading sensor to a deflector surface reference for obtaining the deflector heading which can be used in estimation of the deflector angle of attack.
Techniques for geophysical surveying include marine geophysical surveying, such as seismic surveying and electromagnetic surveying, in which geophysical data may be collected from below the Earth's surface. Geophysical surveying has applications in mineral and energy exploration and production to help identify locations of hydrocarbon-bearing formations. Certain types of marine geophysical surveying, such as seismic or electromagnetic surveying, may include towing an energy source at a selected depth—typically above the seafloor—in a body of water. One or more streamers also may be towed in the water at selected depths—typically above the seafloor—by the same or a different vessel. The streamers are typically cables that include a plurality of geophysical sensors disposed thereon at spaced apart locations along the length of the cable. Some geophysical surveys locate sensors on ocean bottom cables or nodes in addition to, or instead of, streamers. The geophysical sensors may be configured to generate a signal that is related to a parameter being measured by the geophysical sensor. At selected times, the energy source may be actuated to generate, for example, seismic or electromagnetic energy that travels downwardly into the subsurface rock. Energy that interacts with interfaces, generally at the boundaries between layers of rock formations, may be returned toward the surface and detected by the geophysical sensors on the streamers. The detected energy may be used to infer certain properties of the subsurface rock, such as structure, mineral composition and fluid content, thereby providing information useful in the recovery of hydrocarbons.
Current marine geophysical survey techniques may utilize multiple streamers towed at selected lateral distances from one another. Spreading devices are commonly used in geophysical surveying to achieve the desired lateral spread between the streamers. The spreading devices may include a variety of devices, such as doors, paravanes, steering rudders, collectively referred to herein as “deflectors.” Vessel motions and water currents can produce a rather high variance of uncertainties in the estimation of deflector angle of attack.